U.S. patent application number 12/215827 was filed with the patent office on 2009-01-22 for purification process using microchannel devices.
Invention is credited to Francis Joseph Lipiecki, Stephen G. Maroldo, Deodatta Vinayak Shenai-Khatkhate, Robert A. Ware.
Application Number | 20090020010 12/215827 |
Document ID | / |
Family ID | 39941804 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090020010 |
Kind Code |
A1 |
Lipiecki; Francis Joseph ;
et al. |
January 22, 2009 |
Purification process using microchannel devices
Abstract
This invention relates to methods of removing impurities from
compounds having similar volatilities to form ultra high purity
compounds.
Inventors: |
Lipiecki; Francis Joseph;
(Haddonfield, NJ) ; Maroldo; Stephen G.; (Ambler,
PA) ; Shenai-Khatkhate; Deodatta Vinayak; (Danvers,
MA) ; Ware; Robert A.; (Wellesley, MA) |
Correspondence
Address: |
ROHM AND HAAS COMPANY;PATENT DEPARTMENT
100 INDEPENDENCE MALL WEST
PHILADELPHIA
PA
19106-2399
US
|
Family ID: |
39941804 |
Appl. No.: |
12/215827 |
Filed: |
June 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60961370 |
Jul 20, 2007 |
|
|
|
61065473 |
Feb 12, 2008 |
|
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Current U.S.
Class: |
95/106 ;
95/95 |
Current CPC
Class: |
B33Y 80/00 20141201;
B01D 3/14 20130101 |
Class at
Publication: |
95/106 ;
95/95 |
International
Class: |
B01D 53/02 20060101
B01D053/02 |
Claims
1. A method for preparing compounds of ultra high purity
comprising: separating at least one target compound from at least
one impurity compound in at least one microchannel device; wherein
the at least one target compound and at least on impurity compound
have a relative volatility of less than or equal to 1.2; and
further wherein the at least one target compound has a resultant
purity of 99.99%.
2. The method of claim 1 wherein the at least one microchannel
device is a microchannel distillation device.
3. The method of claim 1 wherein purifying in at least one
microchannel device is by temperature swing adsorption.
4. The method of claim 1 further comprising at least one
microchannel device that contains a wick structure.
5. The method of claim 1 wherein the microchannel device has a
height equivalent theoretical plate (HETP) of less than 5 cm.
6. The method of claim 1 wherein the level of the at least one
impurity is reduced to less than 100 ppm of the at least one target
compound and at least one impurity compound combined.
7. The method of claim 1 wherein the at least one microchannel
device is used in combination with at least one other purification
process.
8. The method of claim 1 wherein the target compounds having a
resultant purity of 99.99% are used in electronic materials
applications.
9. The method of claim 7 wherein the target compounds having a
resultant purity of 99.99% are used in electronic materials
applications.
Description
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119(e) of U.S. Provisional Patent Application No.
60/961,370 filed on Jul. 20, 2007 and U.S. Provisional Patent
Application No. 61,065,473 filed on Feb. 12, 2008.
[0002] This invention relates to methods of removing impurities
from compounds having a relative volatility equal to or less than
1.2, to form ultra high purity compounds.
[0003] There are many unmet needs for ultra high purity compounds
for use as feeds, intermediates, solvents or final products in
materials processing and applications. As used herein, ultra high
purity is defined as purity ranging from lower limits of 10.sup.-10
wt % (1 ppt) to upper limits of 0.01 wt % (100 ppm). These
compounds include but are not limited to distillable organics,
including monomers, solvents for chromatographic applications such
as HPLC, sublimable solids, electronic chemicals, and analytical
reagents.
[0004] Traditional methods to purify compounds include
distillation, crystallization, extraction, absorption, adduct
purification, mass-selective ultracentrifuge, and chemical
treatment combined with distillation. These methods and other
related methods, such as the distillation method disclosed in US
Patent Publication No. US 2006/0016215A1 are often limiting because
of the close boiling nature or low relative volatility of the
desired compound and impurity(s), and the low impurity
concentration and driving force for mass transfer. Compounds with a
low relative volatility, .alpha., (.alpha.=vapor pressure of
impurity/vapor pressure of desired compound) equal to or less than
1.2 are especially difficult to purify by staged processes
employing vapor/liquid equilibrium thereby making ultra high purity
materials unattainable by the conventional methods. Furthermore,
there is often an economic constraint to the purity levels
attainable with existing methods. Excessive capital or operating
costs can limit the attainable purity due to unacceptable yield
loss, energy input, or process cycle time due to the physical
and/or chemical properties of the impurities and the compound.
[0005] For example, it is possible to estimate the minimum number
of equilibrium stages required for distillation based on the
relative volatility (.alpha.) of the components and the desired
purity using the Fenske Equation. To remove the most problematic,
near boiling impurities (.alpha.<1.2), the number of stages, or
height equivalent theoretical plates (HETP), can exceed 50, 100, or
even 200 which can require a column height of >10 meters even
with today's most advanced packings (HETP=0.05 to 0.20 m). A column
of this size poses difficult scale-up and operability challenges
and safety concerns from the large inventory of compounds for many
applications.
[0006] Accordingly, there is an ongoing need for a more economical
and efficient process for purifying compounds having impurities
with a relative volatility equal to or less than 1.2.
[0007] The present invention meets this foregoing need by drawing
upon the benefits of microchannel devices in combination with known
techniques for purification. Microchannel devices provide better
control of process conditions, improved safety, and speed to market
from laboratory development to commercial manufacturing. These
devices are extremely useful for purification of reagents,
solvents, intermediates, or final products. The basis for the
observed benefits provided by microchannel technology arises from
the small dimensions and high surface area provided in the device
which enables high exchange rates between phases. Enhancement of
purification is achieved in the microchannel architecture
dimensions, typically 1 to 1000 microns, through an increased
importance of capillary and interfacial phenomena, and reduced
distances for heat and mass-transfer. The superior heat and mass
transfer in these devices provides high exchange rates between
phases and better temperature control for more efficient
purification stages or lower height equivalent theoretical plate
(HETP), thus enabling more stages for higher purity in a fixed
purification device geometry. Furthermore, there are benefits in
lower capital intensity and lower operating costs through improved
energy efficiency by better integration of heat exchange. The
microchannel device further enables production scale-up by
"numbering-up" or merely duplicating the single channel many times,
rather than conventional scale-up, which increases the size of
reactor vessels as scale increases, to meet market demand with no
performance loss and at significant time and cost savings without
the need for traditional process scale-up studies.
[0008] In the present invention there is provided a method for
preparing compounds of ultra high purity comprising:
[0009] separating at least one target compound from at least one
impurity compound in at least one microchannel device;
wherein the at least one target compound and at least on impurity
compound have a relative volatility of equal to or less than 1.2;
and further wherein the at least one target compound has a
resultant purity of 99.99%.
[0010] As used herein, by "microchannel device" is meant a
microstructured device (generally, but not exclusively) with
three-dimensional structures (channels or spaces for fluid flow),
with dimensions perpendicular to flow which are typically 0.1 to
5,000 micrometers, and more specifically between 10-1,000
micrometers
[0011] There are a variety of fabrication techniques and materials
of construction for the microchannel devices of the present
invention. Some materials of construction include but are not
limited to metals, polymers, silicon, ceramics, and glass. Table 1
below, illustrates some of the available fabrication techniques for
each type of microchannel devices:
TABLE-US-00001 TABLE 1 Metals Polymers Silicon Ceramics Glass
Mechanical Molding Lithography Ceramic injection Isotropic etching
micromachining molding Laser Injection molding Anisotropic Tape
casting Microstructuring micromachining dry etching of
photoetchable glass Wet Hot embossing Deep Stereolithography Laser
patterning Chemical reactive ion Etching etching Selective Polymer
laser Anisotropic Coatings and Laser micromaching wet etching foams
Melting Shims Microstereolithography Isotropic etching
[0012] Optionally, the microchannel device of the present invention
contains a wick structure. The wick structure helps to increase
interfacial exchange area and maintain the liquid and vapor phases
in discrete regions of the device to minimize backmixing which
degrades performance. The wick structure can be any type currently
known to those of skill in the art. The microchannel devices of the
present invention may have a HETP ranging from less than 5 cm to
less than 0.25 cm. In some cases the HETP of the microchannel
device is less than 0.05 cm.
[0013] Microchannel devices as aforementioned are useful because
they increase heat and mass transfer. Heat and mass transfer are
increased by the configuration or way in which the microchannel
devices are constructed and operated. Smooth channel walls aid in
increasing heat and mass transfer. Other structural features on the
channel walls such as grooving, texturing and patterning also aid
to increase the heat and mass transfer of the device making the
device more efficient. Any material comprising at least one target
compound and at least one impurity compound having a relative
volatility of equal to or less than 1.2 can be separated by feeding
the sample materials through a microchannel device. As used herein,
by "target compound" is any compound in which one is attempting to
obtain a predetermined purity level post-purification. As used
herein, by "impurity compound" is meant any material that is
combined with the target compound that is intended to be separated
from the target compound. In the present invention there is at
least one target compound which will be separated from at least one
impurity compound. It is an object of the present invention to
separate at least one target compound from at least one impurity
compound such that the resultant target compound has a purity of at
least 99.9999%, at least 99.999%, or at least 99.99%. This level of
purity can be achieved using microchannel devices alone or these
devices in combination with other known purification
techniques.
[0014] The microchannel device may be employed alone or in
conjunction with other known purification techniques. One class of
techniques is adsorptive or chemical purification such as
adduct-purification by temperature swing adsorption. A selective
adsorbent or adduct-forming Lewis base such as an amine, phosphine,
or ether can be supported on microchannel surfaces, providing very
high exchange area to contact the impurity-containing stream. Other
microchannels can be provided for flow of heat transfer fluid for
precise temperature control of the device to efficiently regulate
and cycle between the adsorption and desorption steps. The
microchannel devices may be employed in conjunction with chemical
purification processes such as those employing ionic liquids as
purification agents. To illustrate, metalorganic compounds are
purified by mixing the impurity-containing metalorganic compounds
with an ionic liquid and heating the resultant mixture followed by
the separation and isolation of ultra-pure metalorganic compound.
This method may be used in conjunction with a microchannel device
to substantially reduce metallic, organic and organometallic
impurities present in the target metalorganic compounds. This
combinatorial method provides metalorganic compounds having reduced
levels of silicon-containing impurities as compared to those
obtained using conventional purification processes, in order to
meet the stringent purity criteria (all impurities <10 ppb)
required in semiconductor industry.
[0015] Ionic liquids are generally salts that are liquid at low
temperatures, having melting points under 100.degree. C. Many ionic
liquids remain in liquid at room temperature, and are referred to
as room temperature ionic liquids. Ionic liquids are composed
entirely of ions and typically they are composed of bulky organic
cations and inorganic anions. Due to the high Coulumbic forces in
these compounds, ionic liquids have practically no vapor
pressure.
[0016] Any suitable ionic liquid may be employed in the present
invention. Exemplary cations used in ionic liquids include, but are
not limited to, a hydrocarbylammonium cation, a
hydrocarbylphosphonium cation, a hydrocarbylpyridinium cation, and
a dihydrocarbylimidazolium cation, shown below as Types I-IV,
respectively. Exemplary anions useful in the present ionic liquids
include, but are not limited to, a chlorometalate anion, a
fluoroborate anion such as tetrafluoroborate anion and a
hydrocarbyl substituted fluoroborate anion, and a fluorophosphate
anion such as hexafluorophosphate anion and a hydrocarbyl
substituted fluorophosphate anion. Examples of chlorometalate
anions include, but are not limited to, chloroaluminate anion such
as tetrachloroaluminate anion and a chlorotrialkylaluminate anion,
chlorogallate anions such as chlorotrimethylgallate and
tetrachlorogallate, chloroindate anions such as tetrachloroindate
and chlorotrimethylindate.
##STR00001##
##STR00002##
##STR00003##
##STR00004##
In the above formulae of Types I-IV, R.dbd.H,
(C.sub.1-C.sub.10)alkyl such as methyl, ethyl, propyl, butyl,
pentyl, hexyl and octyl; aralkyl such as benzyl; alkenyl such as
allyl; aryl such as phenyl; or
di(C.sub.1-C.sub.6)alkylamino(C.sub.1-C.sub.10)alkyl such as
dimethylaminomethyl, dimethylaminoethyl, dimethylaminopropyl and
diethylaminopropyl; and X is a halide, such as chloride. Each R
group may be the same or different.
[0017] Other purification processes, such as distillation,
stripping, extraction, and adsorption, based on microchannel device
technology provide the enhanced heat and mass transfer required to
achieve ultra high purity products (ppm, ppb, ppt). These
purification processes additionally provide the intensification of
transfer stages needed to solve the problem of purifying fluid
mixtures with similar boiling points (relative volatility,
0.8<.alpha..ltoreq.1.2) to high purity levels. Advantageous
operating conditions include temperatures and pressures where one
or more of the fluid components in the liquid phase is capable of
undergoing a phase change either to the vapor state or to an
adsorbed state on a sorbent. This can include temperatures from
-25.degree. C. to 250.degree. C., and pressures from 0.1 Pa to 10
MPa. Feed impurity levels can range from 1 ppm up to 10 wt % or
even 50 wt % of the fluid mixture.
[0018] The microchannel devices may be used to purify a variety of
compounds. The impurities of the compounds of the present invention
typically have relative volatility of less than 1.5 and are
difficult to purify by traditional distillation methods. More
preferably, the relative volatility of the impurities in the
compound include .alpha..ltoreq.1.2. Distillable organics, such as
monomers, find utility in the synthesis of polymers for high value
applications where ultra high purity is required to meet stringent
product requirements for food, drug, or human healthcare
applications. These can include pharmaceutical devices for drug
delivery, human healthcare diagnostics, human implantable devices,
and ion exchange resins for purification/production of biological,
pharmaceutical, or nutraceutical compounds. One means to achieve
ultra high purity polymer products is to reduce the impurities in
the starting monomers.
[0019] Other applications for high purity monomers include the
production of low volatile organic content (VOC) acrylic latex
paints. In particular, production of low VOC paints derived from
butylacrylate requires the removal of close boiling impurities in
the monomer as one means to reduce residual VOCs in the final
product. Low VOC paints are characterized as having volatile
impurity levels of 100 ppm or less. One particularly troublesome
close boiling impurity is dibutylether (bpt=140.degree. C.) which
boils close to butyl acrylate (bpt=145.degree. C.) and has a
relative volatility, .alpha.=1.20. Purification of butylacrylate by
use of traditional distillation columns today requires high capital
investment and high operating costs. The method of the present
invention produces a purer product in a much more efficient and
cost effective manner.
[0020] Ultra high purity monomers are especially useful in
manufacture of specialty polymers for applications including photo
lithography and opto-electronics. In some cases, it is necessary to
remove optical isomers of one monomer to get the desired polymer
properties.
[0021] Furthermore, ultra high purity monomers and solvents for
electronic materials applications can include a variety of organic
chemicals such as substituted acrylates and methacrylates, acetone,
MTBE, PGMEA, cyclohexanone, and DMF. These monomers and solvents
are used in the production of photolithographic polymers and
ancillary products for silicon chip fabrication for integrated
circuits. Computer chip manufacturers also use a variety of
solvents, chelating agents, and cleaning solutions as post-etch
residue removers to wash silicon wafers during fabrication. Ultra
high purity product specifications dictate the use of high purity
materials in all aspects of chip processing.
[0022] The microchannel devices can further be combined with one or
more other purification processes to form hybrid purification
processes to bypass compositional or thermodynamic barriers in
solubility or vapor-liquid equilibrium or that otherwise prevent
high purity products from being attained. These include, but are
not limited to, extractive distillation, azeotropic distillation,
extractive crystallization, membrane permeation/distillation,
reverse osmosis/distillation, reactive distillation, catalytic
distillation, stripping distillation and other hybrid purification
processes known to those skilled in the art.
[0023] In extractive distillation the relative volatility of the
feed components is altered by addition of solvent or other added
stream to selectively interact with at least one of the components
to increase the relative volatility of at least one component and
enable an easier separation and purification. The choice of solvent
can impact whether the desired product is recovered as an overhead
product or bottoms product. The choice of solvent will be dictated
by the nature of the compounds to be purified and may include a
range of materials such as water, organic hydrocarbons and ionic
liquids. The added solvent is typically recovered in a separate
solvent recovery column and recycled to the extractive distillation
column. The microchannel device can be used for the extractive
distillation column, the solvent recovery column, or both. Improved
efficiency in separation (lower HETP) provided by the microchannel
device can help overcome the limitations in purity attained by
higher recycle ratio which dilutes the concentration and efficiency
of the extractive solvent in conventional columns.
[0024] In azeotropic distillation a solvent is added to create or
alter a compositional pinch-point with one or more of the feed
components. The azeotrope produced as an overhead or bottoms
product in a first column is sent to a second column where the
azeotrope is broken by addition of a solvent, and the desired
purified stream recovered as an enriched product. The mixed
solvent/feed stream is further processed to recover and recycle the
solvent to the second (azeotropic distillation) column, and reject
the byproducts/impurities from the first column.
[0025] In extractive crystallization processes a solvent is added
to change the relative solubility of two or more solutes to affect
the crystallization process. This could include alteration of a
compositional eutectic that prevents a pure phase from forming, or
temperature insensitive solubility curves that prevent a pure
substance from easily being separated and isolated by adjusting
temperature. Distillation is used to recover and recycle the
solvent to affect the solubility behavior. High efficiency
microchannel distillation provides a unique way to ensure high
purity solvent is present in the recycle which helps improve
efficiency of the crystallization process and reduces the flow and
costs associated with the solvent stream.
[0026] In membrane and/or reverse osmosis distillation hybrid
purification systems a distillation column is coupled with a
membrane separation device to enhance the effectiveness of the
purification process. In one embodiment, the feed stream may first
be processed through a membrane to concentrate the feed stream and
reduce the size of the downstream distillation column. In a second
embodiment, a product from the distillation column may be passed to
a membrane device for a secondary purification or polishing
step.
* * * * *